1. Field of the Invention
This invention relates to ship unloading apparatus and more particularly to bulk flow belt feeder gates for discharging bulk material such as mineral ore or the like from a ship hold onto an unloading conveyor belt beneath the ship hold, and to the combination with such a bulk flow belt feeder gate of a striker plate whose position is coordinated with the open or closed position of the bulk flow belt feeder gate to control the cross-sectional shape of the load of bulk material passing from beneath a given gate onto the conveyor belt downstream of the given gate, the striker plate cooperating with the associated bulk flow belt feeder gate to provide what in effect is a bulk material flow metering action which determines the tonnage of bulk material delivered by the belt conveyor per unit time.
2. Description of the Prior Art
It has been known in the prior art to unload bulk material, such as mineral ore, for example, onto a conveyor belt from a stock pile in the hold of a ship through what is known as a "bulk flow belt feeder gate" at the lower end of the ship hold, the bulk material being unloaded through the bulk flow belt feeder gate onto an underlying conveyor belt which carries the material thus unloaded to a suitable discharge point of the conveyor system.
A "bulk flow belt feeder gate" as known in the prior art, and in the sense used in the present patent application, is a gate which underlies bulk material (such as mineral ore, etc.) in a ship hold or hopper, and which when opened, permits a substantially uncontrolled flow of the bulk material to drop from the hold or hopper onto an underlying conveyor belt. The "bulk flow belt feeder gate" is usually either fully open or fully closed and is not usually so constructed or arranged as to be in a partially open or partially closed condition to provide control of the flow of bulk material to the underlying belt.
In the prior art, a "striker plate" has always been associated with the bulk flow belt feeder gate, the purpose of the striker plate being to serve, in effect, as a template whose shape determines the cross-sectional contour of the load of material dragged out on the conveyor from the uncontrolled quantity of bulk material dropped onto the belt conveyor by the bulk flow feeder gate. Thus, the striker plate of the prior art and also of the present invention cooperates with the associated bulk flow belt feeder gate to provide what in effect is a bulk material flow metering action which determines the tonnage of bulk material delivered by the belt conveyor per unit time.
To the best of my knowledge, in the prior art, the striker plate has always been fixed in a "down" or operative position. Since the striker plate associated with the prior art bulk flow feeder gate was always in the "down" position, it was only practical to have one bulk flow belt feeder gate deposit bulk material onto a given conveyor, since a plurality of bulk flow belt feeder gates feeding a common conveyor belt with each gate having an associated striker plate in the conventional fixed "down" position would result in material deposited on the conveyor belt from a given bulk flow belt feeder gate being interfered with by the "down" position striker plates of bulk flow belt feeder gates feeding the same given conveyor and lying downstream of the given gate and in the path of movement of the bulk material deposited on the belt from the given gate.
For the reasons just given, in the prior art where it was desired to have several feed points onto a given conveyor, arrangements for loading the bulk material other than "bulk flow belt feeder gates" have been used, such as manually operated control gates which require an operator to regulate the flow from the gate to the belt, or other types of gates, such as vibrating gates, for example, which provide a controlled flow of the bulk material onto the belt. Such other alternatives are more expensive to operate or install than the bulk flow belt feeder gate. The bulk flow belt feeder gate has the advantage that it has few moving parts, requires very little head room, is relatively inexpensive, and, in conjunction with its associated striker plate, loads the belt to a desired cross-section automatically. However, as previously pointed out, it has only been practical in the prior art to use one bulk flow belt gate for a given conveyor belt.